Country-wide, sheep have been struggling to feed lambs with less than adequate nutrition. This will have taken its toll on their body condition.
Sheep veterinary consultant, Fiona Lovatt, director of Flock Health, is urging farmers to prioritise thin ewes, even if it means selling some lambs as stores.
It may seem early to start preparing for tupping, however follicles begin their maturation cycle up to six months before the breeding season and ewe BCS can impact the rate and quality of ovulation later in the season.
Dr Lovatt says: “Some years you can wing it, but not this year. Farmers need to be proactive and start preparing for tupping now.
Between weaning and tupping is the golden time for sorting out ewe condition.”
Ewes which are severely nutritionally stressed in the spring and summer have been found to produce poorer quality follicles, which has a knock-on effect on the resultant lamb crop.
“The effects would not necessarily be seen in lambs which are going to slaughter,” Dr Lovatt adds.
“However lambs born from ewes who were under severe nutritional stress pre-tupping and kept as flock replacements have been found to have significantly lower levels of lifetime production.”
Dr Lovatt says in order to mitigate the effects of the poor grass-growing year so far, farmers must be on the case with condition scoring.
“Ideally, wean lambs at 12 weeks old rather than 16 weeks, allowing ewes a longer dry-period and less competition for grass.
“At weaning, or at least two months before tupping, farmers should be condition scoring ewes and splitting them into groups according to their BCS. If they are familiar with the numerical system, split them numerically. If not, fit, fat and thin groups will suffice.”
Fat ewes, if any, can be placed on poorer pasture to lose a little condition, but this can become counter-productive if intake drops below the requirement for maintenance, which can have a negative impact on foetal development.
Fit ewes need to maintain their BCS until tupping. Thin ewes need to be the priority.
Lowland flocks should be targeting a BCS of 3.5 at tupping. One point of body condition is equivalent to 10 to 13 per cent of bodyweight, so for an average 70kg ewe, this amounts to seven to nine kilos.
For maintenance purposes, a ewe requires 8.4MJ of metabolisable energy (ME) per day.
In order to lift its BCS by one point, a 70kg ewe requires a weight gain of approximately seven kilos. This requires an extra 7MJ of ME per day, which equates to 700MJ, over a 100-day weaning to mating period. The total daily requirement of energy is 15.4MJ.
Grass provides an approximate ME value of 10MJ/kg DM meaning the ewe requires an additional 70kg DM on top of requirements for maintenance. It usually takes six to eight weeks on grass alone to gain one point of body condition. However with grass growth stagnant, this extra forage may be difficult to come by.
For thin sheep, requiring more than one point increase in BCS, it may be necessary to consider buffer feeding a concentrate, or to allow more time for weight gain to take place. Sometimes ewes are not capable of consuming the amount of DM required per day to increase their BCS in the available time.
Farmers should look at the forage they have available and its quality, identifying how much forage will be needed over the winter and how much, if any, available for use now will help to contribute towards the shortfall in grass.
“Inevitably some lambs will need to be sold as stores to free-up grass for the ewes and ensure they are not suffering throughout the next pregnancy and lactation as well. Ewes must be the priority,” Dr Lovatt adds.
“Bigger lambs should be sold as soon as possible. As they get older their feed conversion efficiency decreases.
“It may be beneficial to consider buffer feeding some concentrate to the mid-section of lambs to improve them before selling them. It may be necessary to sacrifice the quality of smaller and poorer lambs to avoid paying high prices for concentrate to finish them.”
If ewes enter their next pregnancy in a low BCS, there is little chance they will make up for it before their next lactation. It is difficult to manipulate BCS once ewes are pregnant, explains Dr Lovatt.
Flushing is a secondary tool and short-term fix for ewes still not quite at the correct BCS in the last two to six weeks before tupping. The limiting factor to the success of flushing is the level of nutrition and consequently the BCS of the ewes prior to flushing.
Ewes in the target band for BCS should already have good ovulation rates and may not be improved by increasing the plane of nutrition. However, ewes which are below the target band are expected to benefit greatly as there is a reduction in ovulation rate for each point below target BCS.
Older ewes which are below the target band can often ovulate to a very high rate as a result of flushing, resulting in an increased incidence of triplets and further complications later in pregnancy.
“Rams should be between score three and four. They don’t want to be over-conditioned, as this affects libido and semen quality. However, they do need to be able to make it through the tupping period,” Dr Lovatt adds.
AHDB recommend that rams are fed a high protein diet from ten weeks pre-tupping – 500g of an 18 per cent crude protein feed per day can help to improve semen quality and quantity.
New rams should be purchased well in advance of the mating season to allow them three weeks to adjust to their new diet and changes of system or environment.
Furthermore, in hot weather it is common for rams to be subject to testicular degeneration. Instead of the testicles being cooled by sweat produced by glands on the scrotum and hanging away from the body, rams are often lying, causing increases in the temperature of their testicles and in-turn, degeneration of the tissue.
Ensure rams are shorn early in the summer, have plenty of water and shade and are not over-fat.